Adjustable fasteners have many uses in leisure, camping, sports and safety products, where it is desired that a strap or belt be adjustably secured. Examples include seat belts for automobiles, shoulder straps for backpacks or luggage, and the adjustable straps for life jackets. For safety and secureness in operation it is desirable that the buckle retain the adjustable straps in place until the operator purposely releases the strap. Unintentional or accidental release of the adjustable strap can result in premature disengagement of the object secured by the strap.
While a large number of fasteners are well known, reliable and economic fasteners suitable for mass production that provide secure retention of adjustable straps are difficult to make. Among the drawbacks of known fasteners is that the angle of release of a strap held by frictional engagement may be insufficient to prevent accidental release of the strap.